Guide wires are commonly used in the field of medicine. They are used to navigate the torturous pathways of anatomy. Guide wires, also called stylets, can be inserted through an orifice of a body, or surgically inserted. The wire is pushed, turned, and flexed at a proximal end which remains outside the body. The forces applied to the proximal end translate down the wire to a distal end. The distal end can provide various procedure specific functions inside the body. A guide wire can be made from various materials, with metal being common. Guide wires also come in a wide range of diameters, typically being 0.050 inches or less. Guide wire coatings and finishes can provide benefits for a given procedure. A common application for a guide wire is with endovascular procedures.
The practice of repairing an artery through the use of a stent is well known in the field of medicine. In general and as an example of a typical guide wire application, a guide wire is inserted into an artery using the Seldinger technique. The femoral artery, near the groin, is a common entry point. The guide wire is advanced to a desired location. A delivery catheter with a stent attached is placed around the guide wire through a central lumen and is advanced along the length of the guide wire. Depending on the type of stent, the stent may be deployed by expansion of a balloon or in the case of nitinol stents, by withdrawing a sheath covering the nitinol stent and allowing the nitinol stent to assume its memory shape through self-expansion. A well known issue with self-expanding nitinol stents is their tendency to “jump” as the sheath on the delivery catheter is retracted, which limits the precision of the stent deployment and can result in malposition of the stent. Once the stent is deployed, the delivery catheter is removed from the body.
A recent advancement in the treatment of cardiac disease is transcatheter devices to either replace or repair dysfunctional native cardiac valves. These include the aortic, mitral, tricuspid and pulmonary valves. Rather than using an open-heart procedure to replace or repair a defective valve in a patient's heart, a minimally invasive catheter system is used to deploy an expanding structure containing a replacement valve material. The new prosthetic valve displaces the leaflets of the defective valve and takes over the function of regulating blood flow through the heart and artery. Transcatheter prosthetic valve technology is dominated by two technologies. The first uses a stainless steel (or other metal composition) stent that is expanded by an inflatable balloon. The second utilizes a nitinol metallic mesh that is cooled and compacted, and then expands to a desired shape when the metal approaches body temperature.
Transcatheter valve replacement presents marked challenges over other endovascular procedures that utilize a catheter. Unlike typical endovascular procedures which occur in constrained tubular blood vessels where there is limited spatial movement of the devices, transcatheter valve procedures by their nature are performed in the heart with relatively large and spatially complicated chambers that pose significant challenges to guidewire management and device manipulation by the surgeon. First, the prosthetic valve must be located extremely precisely relative to the natural valve prior to the prosthetic valve being expanded in place. The replacement valve needs to be located plus or minus 1-3 mm in depth relative to its target location. The surgeon may use fluoroscopic imaging to determine optimal depth of the valve prior to deployment. From the proximal end, the surgeon manipulates the guide wire and catheter sheath to achieve the desired deployment location of the prosthetic valve. An improperly deployed valve can lead to perivalvular regurgitation or catastrophic embolization of the device into either the heart or aorta. Second, in order to minimize canting of the prosthetic valve, the deployed valve should be positioned ideally in the center of the diseased native valve. Again, the surgeon uses forces on the proximal end of the guide wire and catheter to attempt to manipulate the location of the valve relative to the walls of the defective valve. Third, during the procedure the surgeon in addition to maintaining optimal forces on both the catheter sheath and guide wire, has additional responsibilities of managing the operating room, and scanning fluoroscopic, echocardiology and hemodynamic monitors. When the replacement valve is optimally located, the surgeon must maintain optimal pressure on both the guide wire and the catheter to resist translational forces created by the expanding valve. Wherein many endovascular procedures utilize the guide wire only for navigation purposes, in new advanced procedures such as transcatheter aortic valve replacement, the guide wire is often the key element throughout the procedure and requires constant attention. The transcatheter aortic valve replacement guide wire provides navigation of the catheter sheath as well as impacting location of the deployed valve. With guide wires being small in diameter, often coated in low friction materials, and with bodily fluids present, maintaining optimal pressure on the guide wire throughout the valve replacement procedure can be challenging and fatiguing for the surgeon. Although the field of transcatheter mitral valve replacement and repair is less mature than transcatheter aortic valve replacement, the challenges of accurate device deployment may be even greater due to the factors outlined above.
In these respects, the present invention departs from conventional concepts of the prior art by providing a guide wire control device for use in catheter based medical procedures. The present invention also provides an improved way to achieve optimal valve deployment in transcatheter valve replacement and repair procedures.